Concise Summary of Anaplasma phagocytophilum in Dogs


Epidemiological and Clinicopathological Features of Anaplasma phagocytophilum Infection in Dogs: A Systematic Review.

El Hamiani Khatat S, Daminet S, Duchateau L, Elhachimi L, Kachani M, Sahibi H.

Front Vet Sci. 2021 Jun 23;8:686644.

  • Pathogen Overview:
    Anaplasma phagocytophilum is a zoonotic, tick-borne bacterium, predominantly transmitted by Ixodid ticks, affecting multiple mammalian species, including dogs and humans.

  • Epidemiology:

    • Canine granulocytic anaplasmosis (CGA) is increasingly identified, with significant cases reported in the USA, Europe, and Asia.

    • In the USA, the number of human cases rose significantly (53% increase from 2008-2010).

    • Data on canine infections are less comprehensive, but several studies indicate high seroprevalence in some areas, correlating with human cases.

  • Clinical Manifestation:

    • Symptoms include lethargy, inappetence, weight loss, fever, and musculoskeletal pain.

    • Hematological abnormalities often seen: thrombocytopenia, anemia, and morulae in neutrophils.

    • Clinical signs can be mild, leading to underdiagnosis despite high seroprevalence.

  • Clinical Diagnosis:

    • Diagnosis is complicated by variations in clinical signs, potential co-infections (e.g., with Borrelia burgdorferi), and lack of specific symptoms.

    • Laboratory confirmation through PCR and identification of morulae in blood smears is crucial.

  • Genetic Variability:

    • Strains exhibit considerable genetic diversity, affecting pathogenicity and host tropism, with potential implications for varying disease severity in different host species.

  • Vector Transmission:

    • Predominantly transmitted via Ixodes ticks, with different species involved in different geographical areas.

    • Environmental factors contribute to tick presence; increased exposure correlates with higher incidence of diseases.

  • Impact on Human Health:

    • Dogs serve as sentinels for Anaplasma phagocytophilum, indicating potential risk for human infections, especially in urban areas where stray dogs can contribute to pathogen dynamics.

  • Treatment and Prognosis:

    • Treatment typically involves doxycycline, with rapid improvement seen in most cases.

    • Complications may arise, and some severe cases can result in immune-mediated conditions such as hemolytic anemia.

  • Research Gaps:

    • More studies are needed on the role of dogs as reservoirs, the ecological factors influencing transmission, and the relationships between strain variability and clinical outcomes.